Add new output "drivers" for video and audio:
- WAV for audio - don't connect to any sound system then
- BMP or PNG for video (bunch of frames) - thus no GUI involved then, don't connect to any GUI system, pure console
the very same way as MPLAYER already does :-)
This way SWF could be "converted" into an "ordinary" movie, for example OGG Theora+Vorbis.

Create a "Gnash-Lite" version:
- Only play SWF files from local storage media, no network, no FLV/Tube/FFMPEG stuff, no browser stuff
- Only "raw" video (+audio) output via SDL or similar or WAV+BMP/PNG, no GUI around, like MPLAYER and QEMU do